When C. was in fourth grade, we made the switch from doing one-on-one "playdates" to having group gatherings once a month or so, on a Friday night.
I'd been telling T. that he could do the same and last week was his first one. As with C., the friends come over for 2 hours. They hang out, then have dessert, then hang out some more. T. chose chocolate fondue for his dessert. Here's pictures from Friday night: